A few Woodstock Low Power questions

[Archilog]

Hello, HP fans!

I am seriously planning to acquire a Woodstock Low Power kit to 'upgrade' a HP-22. I am very grateful to the authors of this prodigious marvel, mainly PANAMATIK, for this opportunity.

It's not only because the Woodstock Series seems to me to be the nicest of all times, but also because the 70's red display is very efficient for a hobby I like to practice: astronomy.

1. Today the HP-67 option "Merge" is not available on the HP-67E, but I've heard something about using datas registers in one program to pass them to another program in another calculator instance. How is this possible, and at what level? What are the performances if I want to register, say, hundred most brilliant stars coordinates in some registers to mathematically treat them in another program (that is: in another calculator)? Is there any limitations to this?

2. Since Panamatik is offering a GPS option, I'm also interested in adding it to my purchase, but I would like to know what precision it can afford; the idea behind this is to use the calc to determine N-E-S-W directions easily. So, what can I expect from this GPS?

3. Woodstock LP kit permits some alphabetical manipulations, but would it be possible to display, for example, the name of a star followed by its coordinates, like on a HP-41?

I would prefer upgrade to the HP-29E or the HP-34E - just a question of practice, after all - but any modification to this may be plan.

Thanks in advance!

Archi.

[Maximilian Hohmann]

Hello!

(05-31-2018 02:37 PM)Archilog Wrote:  2. Since Panamatik is offering a GPS option, I'm also interested in adding it to my purchase, but I would like to know what precision it can afford; the idea behind this is to use the calc to determine N-E-S-W directions easily. So, what can I expect from this GPS?

I leave question 1 and 3 for Panamatik to answer (my guess, after playing with such a calculator since some time would be that with the current firmware the answers are "No" and "No") but I can answer question no. 2:

According to specs the GPS module employed has an accuracy of 3m (10ft). As you will use it stationary mostly the actual accuracy should be better than that because it will average many measurements. It does not contain a compass however (like most smartphones or tablets) so don't expect to get direct direction information from it in stationary mode. You could of course walk a little distance either way and look at the ground track display but this is not going to be very accurate or practical. The cheapest electronic compass (for my telescope I bought one on eBay for 1 Euro, it even features display illumination) will be better suited for the purpose.

Regards
Max

[Archilog]

Thank you, Max, for your accurate answer.

Actually I don't want to use this calc for a fixed station, rather a holiday opportunity or something like that, a place where I may take my calc only... not everything needed to make a real astronomic observation, you know, just to answer: "This planet is Jupiter, not Saturn" to my neighbour (or myself). If I have to walk 30 m. to know where North is (+/- 5°), it's not a big deal.

I know everything is available on a smartphone, and a "simple" Free42 or 15C app might be sufficient for the job - or best: Stellarium.
But I would like to program a 70's red leds calc for this purpose. I am sure a majority here understands that.

I could do the same with an original HP-67, certainly, plus a lot of magnetic cards and batteries to take with, and necessarily knowing where North or South is at the moment. A HP-34E or HP-67E (EX?) would be more efficient...

Regards,

Archi.

[Dave Shaffer]

Stellarium is your best bet! (Take it from a real astronomer! Why reinvent the wheel?)

GPS accuracy is variable. 5-10-15 meters is about as good as you can hope for from a simple one-channel unit, especially if multi-path occurs, and on days with ionospheric disturbance. If it uses something like WAAS, you will get better accuracy. A few meters is certainly good enough to tell you where your telescope is.

If the sky is clear enough to observe, you should be able to see the North Star (assuming you are in the northern hemisphere) - that will give you north to half a degree.

[Maximilian Hohmann]

(05-31-2018 07:26 PM)Dave Shaffer Wrote:  If it uses something like WAAS, you will get better accuracy. A few meters is certainly good enough to tell you where your telescope is.

WAAS has been pretty much standard since some years. The correction signals are transmitted on the same frequencies as the navigation signals so it is just a matter of software. Even the tiny little GPS module Panamatik uses for his Woodstock LP conversions is WAAS/EGNOS/DGPS/Whateveryouwanttocallit capable. I have a similar module in one of my quadcopter drones and that is good enough to make the thing return to it's starting position within a few centimeters.

Archilog Wrote:If I have to walk 30 m. to know where North is (+/- 5°), it's not a big deal.

In that case a Panamatik converted HP-22 would work for you! But for a star catalog with names I'm afraid it would be the wrong tool. The programming capabilites are really limited to those of an original Woodstock series calculator but with more memory.

Regards
Max

NB: I like the LP module so much that I have just acquired three defective Woodstock calculators (which are still in the mail) so that I can fill some gaps in my collection (namely the HP-27 and 29) - until one day, hopefully, I will be able to find the real calculators.

[PANAMATIK]

I agree to the answers shown here.

The LP is not very well suited for storing many star coordinates. It has only 80 or 160 registers per calculator (40 or 80 stars). The LP cannot treat alphanumeric variables like the HP-41. It can only show some messages and program names as text.

However it is possible to merge HP-25 or HP-29 programs during runtime (not HP-67 or others) to run a single very large program. Loading register sets is not a programmble instruction, you can load a register set of 8 or 16 registers only manually.

I know from my own experience that astronomy programs need a lot of accuracy in their algorithms and the HP-25/29 program steps are very limited compared to C/C++ language. Calculating the declination and right ascension of your telescope mount from the star coordinate and the GPS position could be possible but is quite challenging.

Bernhard

[Archilog]

Thank you for these new informations, Bernhard, Max, Dave.
My goal is not to mount a telescope with this machine, I just want to use it when walking (I'm living since 2002 in southern hemisphere where stars are not so familiar to me).
I downloaded the LP manual to understand better how it works - 160 registers is already a good result and being able to surpass the 98-steps capacity with the 29E is very interesting!
But the lack of star naming remains a real difficulty... Well, I'll have to know them anyway, perhaps with some alphanumerical mnemonics.
Thank you again. To everyone.